Fine-Scale Temporal Dynamics of a Fragmented Lotic Microbial Ecosystem

Microbial ecosystems are often assumed to be relatively stable over short periods of time, but this assumption is seldom tested. An urban stream influenced by both flow and varying levels of anthropogenic influences is expected to have high temporal variability in microbial composition, and short-term ecological instability. Thus, we analyzed the bacterioplankton composition of a weir-fragmented urban stream using Automated rRNA Intergenic Spacer Analysis (ARISA). A total of 46 sequential samples were collected in July 2009 for 7 days, every 7 hours, from both the up-stream side of the weir (stream water) and the downstream side of the weir (estuarine) water. Bray-Curtis similarity based analysis showed a clear division between upstream and downstream communities. A sudden pH drop induced change in both communities, but composition stability partially recovered within less than a day. Thus, our results show that microbial ecosystems can change rapidly, but re-establish a new equilibrium relatively quickly

Movement Behavior of High-Heeled Walking: How Does the Nervous System Control the Ankle Joint during an Unstable Walking Condition?

The human locomotor system is flexible and enables humans to move without falling even under less than optimal conditions. Walking with high-heeled shoes constitutes an unstable condition and here we ask how the nervous system controls the ankle joint in this situation? We investigated the movement behavior of high-heeled and barefooted walking in eleven female subjects. The movement variability was quantified by calculation of approximate entropy (ApEn) in the ankle joint angle and the standard deviation (SD) of the stride time intervals. Electromyography (EMG) of the soleus (SO) and tibialis anterior (TA) muscles and the soleus Hoffmann (H-) reflex were measured at 4.0 km/h on a motor driven treadmill to reveal the underlying motor strategies in each walking condition. The ApEn of the ankle joint angle was significantly higher (p<0.01) during high-heeled (0.38±0.08) than during barefooted walking (0.28±0.07). During high-heeled walking, coactivation between the SO and TA muscles increased towards heel strike and the H-reflex was significantly increased in terminal swing by 40% (p<0.01). These observations show that high-heeled walking is characterized by a more complex and less predictable pattern than barefooted walking. Increased coactivation about the ankle joint together with increased excitability of the SO H-reflex in terminal swing phase indicates that the motor strategy was changed during high-heeled walking. Although, the participants were young, healthy and accustomed to high-heeled walking the results demonstrate that that walking on high-heels needs to be controlled differently from barefooted walking. We suggest that the higher variability reflects an adjusted neural strategy of the nervous system to control the ankle joint during high-heeled walking

Culture, Neurobiology, and Human Behavior: New Perspectives in Anthropology

Our primary goal in this article is to discuss the cross-talk between biological and cultural factors that become manifested in the individual brain development, neural wiring, neurochemical homeostasis, and behavior. We will show that behavioral propensities are the product of both cultural and biological factors and an understanding of these interactive processes can provide deep insights into why people behave the way they do. This interdisciplinary perspective is offered in an effort to generate dialog and empirical work among scholars interested in merging aspects of anthropology and neuroscience, and anticipates that biological and cultural anthropology converge. We discuss new theoretical developments, hypothesis-testing strategies, and cross-disciplinary methods of observation and data collection. We believe that the exigency of integrating anthropology and the neurosciences is indisputable and anthropology's role in an emerging interdisciplinary science of human behavior will be critical because its focus is, and has always been, on human biological and cultural systems

Many paths from state to state

Humans and animals can actively represent and maintain information that guides decisions, but how neural circuits achieve this is unknown. The dominant notion for many years has been that neurons encode information primarily using their spike rate, which is usually hypothesized to have a static relationship with stimuli or internal state. Yet more recently there has been a resurgence of interest in the old idea that the brain might use stereotyped sequences of discrete states, switching from one activity pattern to another to maintain activity1, 2. Each of these 'states' would be distinct enough from one another that even an imperfect realization of the activity pattern could still reliably drive the next state in the sequence. These sequences might be used explicitly as clocks3, 4, or they might be a convenient way for recurrent neural circuits to maintain information despite the short time constants of single cells5, 6. It is challenging to perfectly tune a circuit to maintain a precise, stable state along a continuum of possibilities7. The idea that sequences might avoid this challenge is thus appealing and would even permit sparse activity. In this issue of Nature Neuroscience, Morcos and Harvey8 present evidence that this is indeed the case, with a few wrinkles that may make the system more flexible

Bunge’s Requirement of Neurological Plausibility for a Linguistic Theory

Mario Bunge claimed in many places that core hypotheses of mainstream linguistics have been contrasted with theoretical assumptions, but not with empirical evidence. Bunge’s criticism is not only correct for what was known in the middle-1980s, but it also remains valid today. First of all, the very distinction between “faculty of language in the broad sense” (FLB) and “faculty of language in the narrow sense” (FLN) is inconsistent, because it is sometimes presented as an empirical hypothesis and sometimes as a mere terminological or expository aid. Secondly, the Universal Grammar (UG) hypothesis, in any of its forms, is incompatible with biological evidence. Third, the hypothesis that language is a system capable of performing operations on some kind of objects is incompatible with basic neurological evidence, because it assumes (explicitly or implicitly) that the mind/brain is able to store and manipulate objects.Fil: Gil, Jose Maria. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Humanidades y Ciencias Sociales. Universidad Nacional de Mar del Plata. Instituto de Humanidades y Ciencias Sociales; Argentin